Effective community engagement involves at least three functional components, 1) longitudinal pushpull relationships between the research community and communities of practice (clinicians, public health workers, policy makers, etc.), 2) community test sites where innovations and solutions can be developed, tested, and refined, and 3) a dissemination/implementation infrastructure to facilitate the spread and uptake of effective innovations. When these components are functioning well, the need for translation is substantially reduced. Productive interactions between researchers and communities are built upon longitudinal respectful relationships. As discussed in the Oversight and Management Core, these relationships are strengthened by a common mission and rules of engagement. They also require facilitative organizational structures and functions. Productive interactions between researchers and communities include four types of activities. Communities (including clinicians, public health officials, and policy-makers) push problems, observations, innovations, and unanswered questions to researchers and pull expertise, solutions, and answers from them in return. Researchers push discoveries, innovations, and solutions to communities and pull practical knowledge and expertise from communities. Before solutions and innovations are disseminated, implemented, and diffused throughout community delivery systems, they should be tested in a few carefully selected sites. Practice-based research networks, for example, serve as community test sites for practices. Once innovations are ready for widespread use, there must be a system wide infrastructure through which dissemination, implementation, and diffusion can be facilitated. Perhaps the best example of such an infrastructure is Cooperative Extension, in which county extension agents maintain channels of communication and personal relationships between local farm families, experimental farm stations (the PBRNs of agriculture), and land grant colleges. If an important innovation occurs in agriculture, virtually every farmer in the country is likely to hear about it within a few months and have someone locally to help them to implement it.